Notifications

Description

This service is managing Notifications.

Method	Return Type	Description
`[notifications]( filter )`	`Notifications.notification[]`	Get notifications using optional filter (by id or object_type).
`[add]( notification )`	id	Add a new notification. Returns created notification id.
`[update]( notification )`		Update existing notification.
`[remove]( id )`		Remove existing notification.